Multiple polymer belt used as a carrier in a linear belt polishing system

ABSTRACT

A support belt to be used with a polishing belt. The support belt includes an interior layer made of a polymer, wherein said interior layer has a first free end and a second free end that abut one another but are not attached to one another so as to form a first seam and an adhesive placed on an exterior surface of the interior layer. An exterior layer made of a polymer and attached to the adhesive, wherein the exterior layer has a first free end and a second free end that abut one another but are not attached to one another so as to form a second seam.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention regards a polishing pad and belt forpolishing and planarizing semiconductor substrate surfaces.

[0003] 2. Discussion of the Related Art

[0004] As shown in FIG. 1, it is well known in the art to finely polishand planarize semiconductor substrates or semiconductor wafers 100 usingchemical mechanical polishing (CMP) processes. Many of these polishingCMP processes use a polishing system 102 that includes a polishing belt104. As shown in FIG. 1, the polishing system 102 includes a polishingbelt 104 that is configured to revolve over a plurality of belt rollers106. One or more polishing pads 108 (not to scale in FIG. 1) are adheredto the continuous belt 104. In the case of using a single polishing pad,the polishing pad is formed so as to cover the entire exterior surfaceof the continuous belt. In the case of using multiple polishing pads,multiple, individual pad sections are positioned adjacent to one anotheracross the exterior surface of the belt.

[0005] In operation, one or more semiconductor wafers are positionedadjacent to and held against the polishing pad(s). The polishing system102 farther includes a semiconductor support 110 that is operative toplace a semiconductor wafer 100 adjacent the polishing pad 108 and belt104 of the present invention. The polishing system 102 further includesa base 112 on the opposite side of the pad 108 and belt 104 as thesemiconductor wafer 100. The base 112 is operative to prevent therelatively planer surface of the pad 108 and belt 104 that is adjacentthe semiconductor wafer 100 from being deformed by the downward force ofthe semiconductor support 110.

[0006] As the belt revolves, the polishing pad moves to polish andplanarize the semiconductor wafers. There are several requirements for abelt to ensure efficient polishing of semiconductor wafers. Onerequirement is that the belt is strong so as to endure a large number ofpolishing cycles without wearing out. Steel belts have been used in thepast as an attempt to provide such strength. Such steel belts wereformed from a single sheet where the ends were welded to each other toform the belt. One problem with such steel belts was that one or morewelding seams were formed at the areas of attachment. Such seams werecontrary to a second requirement of polishing belts: the belt mustmaintain a flat surface during the polishing surface in order to insureadequate polishing of the semiconductor wafers.

[0007] As an attempt to overcome the above noted deficiencies of steelbelts, there have been attempts at devising a belt that is both strongand seamless. Such belts have included multiple polymer layers formed inthe shape of a belt where fibers/fabrics may or may not be used toprovide reinforcement for the polymer layers. Such belts are formed bypouring the materials into a mold or the free ends of layer strips arewelded to one another. Examples of such belts are disclosed in WO99/06182, WO 24550, WO 01/15867, and U.S. Pat. No. 5,810,964, the entirecontents of which are incorporated herein by reference. One disadvantageof such molded polymeric belts is that the process for forming the beltsis expensive and time consuming.

[0008] Another disadvantage of using welded polymer belts is that theheight of the welded seam is often not uniform. In particular, using thelatest welding techniques with high performance polymer sheets resultsin seams having a step height difference and/or a decrease in thestrength and toughness of the seam. This can be a problem when apolishing material is placed on the belt without taking intoconsideration the inadequacies of the seam.

[0009] Another problem with welded polymer belts is that the welded bondis often not strong enough to be effective for chemical mechanicalpolishing processes and systems.

SUMMARY OF THE INVENTION

[0010] One aspect of the present invention regards a support belt to beused with a polishing belt. The support belt includes an interior layermade of a polymer, wherein said interior layer has a first free end anda second free end that abut one another but are not attached to oneanother so as to form a first seam and an adhesive placed on an exteriorsurface of the interior layer. An exterior layer made of a polymer andattached to the adhesive, wherein the exterior layer has a first freeend and a second free end that abut one another but are not attached toone another so as to form a second seam.

[0011] A second aspect of the present invention regards a polishing beltthat includes a support belt that has an interior layer made of apolymer, wherein the interior layer has a first free end and a secondfree end that abut one another but are not attached to one another so asto form a first seam. The support belt further includes an adhesiveplaced on an exterior surface of the interior layer and an exteriorlayer made of a polymer and attached to the adhesive, wherein theexterior layer has a first free end and a second free end that abut oneanother but are not attached to one another so as to form a second seam.The polishing belt further including a polishing material is depositedon a surface of the exterior layer that faces away from the adhesive.

[0012] A third aspect of the present invention regards a polishingsystem that includes a material to be polished and a polishing belt thatmoves relative to the material and polishes the material as thepolishing belt moves. The polishing belt includes a support belt havingan interior layer made of a polymer, wherein the interior layer has afirst free end and a second free end that abut one another but are notattached to one another so as to form a first seam, an adhesive placedon an exterior surface of the interior layer and an exterior layer madeof a polymer and attached to the adhesive, wherein the exterior layerhas a first free end and a second free end that abut one another but arenot attached to one another so as to form a second seam. A polishingmaterial is deposited on a surface of the exterior layer that faces awayfrom the adhesive.

[0013] The first two aspects of the present invention provide theadvantage of providing a polishing belt that inexpensive and easy tomanufacture.

[0014] Each of the aspects of the present invention provides theadvantage of providing polymer belt that has a uniform surface and hasadequate strength and toughness at a seam so that it can be effectivelyused in chemical mechanical polishing processes and systems.

[0015] Further advantages, as well as details, of the present inventionensue from the following description of a preferred embodiment, makingreference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a side view of a known polishing system that uses aknown polishing belt;

[0017]FIG. 2 is a schematic side view of a first embodiment of apolishing belt with polishing material according to the presentinvention to be used with the polishing system of FIG. 1; and

[0018]FIG. 3 is schematic exploded view of a portion of a secondembodiment of a polishing belt with polishing material according to thepresent invention to be used with the polishing system of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] As shown in FIG. 2, one embodiment of a support belt 200according to the present invention includes an interior layer 202 madeof a polymer, such as Mylar, and an exterior layer 204 made of a polymeralso, such as Mylar. The interior and exterior layers 202 and 204 arepreferably identical in shape defining a rectangle having a length ofapproximately 93.25″, a width of approximately 13″ and a thicknessranging from 7 mil to 14 mil, preferably approximately 14 mil. Thepolymers used for the layers 202, 204 preferably have a high tensilemodulus and have a stretch resistance such that they do not requirereinforced internal layers, such as fibers, metal wires or wovencarcass, that are often used in conventional molded polymeric beltpolishing pads. Note that while it is preferred that the polishing beltdoes not use reinforcing materials, it is possible to adapt thepolishing belt so that one or both of the layers 202, 204 are steelreinforced such as by using metal wire. Such reinforcement would makethe polishing belt stretch resistant during stress situations and wouldalso require layers 202, 204 to be thickened.

[0020] The polishing belt is formed by placing the two free ends 206,208 of the interior layer 202 adjacent to one another as shown in FIG.2. The free ends 206, 208 abut one another so as to define a linear“butted” seam 210. Such a butted seam includes the cases where the freeends 206, 208 touch one another or the free ends 206, 208 are separatedfrom one another by a gap that ranges from zero to a maximum of 3/32″.At this stage, an adhesive 212 is placed over the entire exteriorsurface 214 of the interior layer 202. The adhesive 212 is a high shearadhesive preferably in the form of a roll, such as the adhesives knownby the trade names Adchem 7332, Adchem 1666-2, Adchem 732, Adchem 728,PSA5, PSA12 and VHB. After the adhesive 212 is attached to the interiorlayer 202, a surface 215 of the exterior layer 204 is placed on thesurface of the adhesive 212 facing away from the exterior surface 214 ofthe interior layer 202 so that the exterior layer 204 is attached to theadhesive 212. The adhesive 212 covers the entirety of the surface 215.The free ends 216, 218 of the exterior layer 204 abut one another toform a linear butted seam 220 that is similar in structure to the buttedseam 210 described previously. As shown in FIG. 2, the seams 210 and 220are opposite one another in that the seams 210 and 220 are displaced by180° relative to one another. The displacing of the seams 210 and 220 inthis manner allows for the full amount of shear to take place for thesupport belt 200. Note that other displacements of the seams 210 and 220are possible where the displacements range from 180° to a minimumdisplacement. Preferably, the minimum displacement between the seams isapproximately 4″ or 15.4°. The larger the displacement becomes withrespect to the minimum displacement of 4″ the less likely the seams willmove at the same time.

[0021] Besides providing a full amount of shear, the support belt 200provides other advantages. For example, the use of butted seams that areopposite one another allows for a uniformly thick belt even at the seams210 and 220, where the free ends of the layers 202, 204 are not directlyattached to one another and do not form raised areas, and so acts as aseamless belt. Another advantage is having the adhesive 212 cover theentire exterior surface 214 dramatically increases the shear strength ofthe belt when compared with the case of when the adhesive was appliedonly at the seams 210 and 220. Another advantage of the support belt 200is that it does not require any altering of the belt material as far ascutting or grinding the areas around the seam in order to achieve a moreuniform belt. The lack of cutting and grinding eliminates extrapreparatory steps, which results in a simple design for the belt and abelt that is inexpensive to manufacture.

[0022] Another embodiment of a belt that enjoys many of the advantagesof the support belt 200 is shown in FIG. 3. The support belt 300 has astructure that is similar to that of support belt 200 and so likenumerals are used for like elements. In particular, interior layer 202,exterior layer 204 and the adhesive 212 are attached to one another in amanner similar to that described previously with respect to the supportbelt 200. The only differences are the dimensions of the layers 202, 204and the seams 210 and 220 are displaced by a different amount. Inparticular, the layers 202, 204 each have a length of approximately 12″,a width of approximately 0.5″ and a thickness of approximately 14 mil.The seams 210 and 220 are displaced from one another by a distance of 4″which corresponds to a displacement of approximately 120° relative toone another. The displacing of the seams 210 and 220 in this mannerallows for the full amount of shear to take place for the support belt300.

[0023] After the support belts 200 and 300 are formed, a polishingmaterial 222 is deposited on the exterior surface 224 of the exteriorlayer 204 by various known processes, such as ink jet printing andgravure/screen printing. Any known polishing material 222 may be usedsuch as the material known by the trade name IC1000 made by Rodel. Thepolishing material 222 can be varied to meet a customer's needs. Forexample, specific different polishing materials are used for polishingoxide substrates and metal containing substrates. The polishing material222 may be attached to layer 204 via an adhesive 224. Note that thecombination of the support belts 200, 300 and the polishing material 222is deemed to form a polishing belt 226, 302, respectively.

[0024] Other modifications are possible for the support belts 200 and300. For example, sub-pads can be used in addition to the polishingmaterial 222, such as the sub-pad known by the trade name SP2100 made byRodel. The sub-pads are attached to the exterior surface 224 by anadhesive, such as the adhesives known by the trade names PSA5, PSA12 andPSA2.

[0025] After the polishing materials are attached to the belts 200 and300, the belts are installed in a polishing system such as the onedescribed previously with respect to FIG. 1.

[0026] The foregoing description is provided to illustrate theinvention, and is not to be construed as a limitation. Numerousadditions, substitutions and other changes can be made to the inventionwithout departing from its scope as set forth in the appended claims.

We claim:
 1. A support belt to be used with a polishing belt,comprising: an interior layer made of a polymer, wherein said interiorlayer has a first free end and a second free end that abut one anotherbut are not attached to one another so as to form a first seam; anadhesive placed on an exterior surface of said interior layer; and anexterior layer made of a polymer and attached to said adhesive, whereinsaid exterior layer has a first free end and a second free end that abutone another but are not attached to one another so as to form a secondseam.
 2. The support belt of claim 1, wherein said polymer of saidinterior layer comprises Mylar.
 3. The support belt of claim 2, whereinsaid polymer of said exterior layer comprises Mylar.
 4. The support beltof claim 1, wherein no reinforcing internal layers are present.
 5. Thesupport belt of claim 1, wherein said first seam and said second seamare offset with respect to each other.
 6. The support belt of claim 5,wherein said first seam and said second seam are displaced with respectto each other by an amount that ranges from approximately 15° to 180°.7. The support belt of claim 6, wherein said amount is approximately15°.
 8. The support belt of claim 6, wherein said amount isapproximately 180°.
 9. The support belt of claim 1, wherein saidadhesive is placed over the entirety of said exterior surface.
 10. Apolishing belt comprising: a support belt comprising: an interior layermade of a polymer, wherein said interior layer has a first free end anda second free end that abut one another but are not attached to oneanother so as to form a first seam; an adhesive placed on an exteriorsurface of said interior layer; and an exterior layer made of a polymerand attached to said adhesive, wherein said exterior layer has a firstfree end and a second free end that abut one another but are notattached to one another so as to form a second seam; and a polishingmaterial is deposited on a surface of said exterior layer that facesaway from said adhesive.
 11. The polishing belt of claim 10, whereinsaid polymer of said interior layer comprises Mylar.
 12. The polishingbelt of claim 11, wherein said polymer of said exterior layer comprisesMylar.
 13. The polishing belt of claim 10, wherein no reinforcinginternal layers are present.
 14. The polishing belt of claim 10, whereinsaid first seam and said second seam are offset with respect to eachother.
 15. The polishing belt of claim 14, wherein said first seam andsaid second seam are displaced with respect to each other by an amountthat ranges from approximately 15° to 180°.
 16. The polishing belt ofclaim 15, wherein said amount is approximately 15°.
 17. The polishingbelt of claim 15, wherein said amount is approximately 180°.
 18. Thepolishing belt of claim 10, wherein said adhesive is placed over theentirety of said exterior surface.
 19. The polishing belt of claim 10,further comprising a sub-pad attached to said surface of said exteriorlayer that faces away from said adhesive.
 20. A polishing systemcomprising: a material to be polished; a polishing belt that movesrelative to said material and polishes said material as said polishingbelt moves, wherein said polishing belt comprises: a support beltcomprising: an interior layer made of a polymer, wherein said interiorlayer has a first free end and a second free end that abut one anotherbut are not attached to one another so as to form a first seam; anadhesive placed on an exterior surface of said interior layer; and anexterior layer made of a polymer and attached to said adhesive, whereinsaid exterior layer has a first free end and a second free end that abutone another but are not attached to one another so as to form a secondseam; and a polishing material is deposited on a surface of saidexterior layer that faces away from said adhesive.
 21. The polishingsystem of claim 20, wherein said first seam and said second seam areoffset with respect to each other.
 22. The polishing system of claim 20,wherein said adhesive is placed over the entirety of said exteriorsurface.
 23. The polishing system of claim 20, further comprising aplurality of belt rollers upon which said polishing belt revolves. 24.The polishing system of claim 20, wherein said material comprises asemiconductor wafer.
 25. The polishing system of claim 20, furthercomprising: a support that places said material adjacent to saidpolishing belt; and a base positioned on an opposite side of saidpolishing belt as said material, wherein said base prevents a surface ofsaid polishing belt adjacent said material from being deformed by aforce generated by said support.
 26. The polishing system of claim 24,further comprising: a support that places said semiconductor waferadjacent to said polishing belt; and a base positioned on an oppositeside of said polishing belt as said semiconductor wafer, wherein saidbase prevents a surface of said polishing belt adjacent saidsemiconductor wafer from being deformed by a force generated by saidsupport.